Understanding WDM MUX/DEMUX Ports and Its Application

Wavelength division multiplexing (WDM) is a commonly used technology in optical communications. It combines multiple wavelengths to transmit signals on a single fiber. To realize this process, CWDM and DWDM mux/demux are the essential part. As we all know, there are several different ports on the WDM mux and demux. This article will give a clear explanation to these ports and their applications in WDM network.

Overview of Different Ports on WDM MUX/DEMUX
Line Port

Line port, sometimes also called as common port, is the one of the must-have ports on CWDM and DWDM Mux/Demux. The outside fibers are connected to the Mux/Demux unit through this port, and they are often marked as Tx and Rx. All the WDM channels are multiplexed and demultiplexed over this port.

Channel Port

Like the line port, channel ports are another must-have ports. They transmit and receive signals on specific WDM wavelengths. CWDM Mux/Demux supports up to 18 channels from 1270nm to 1610nm with a channel space of 20nm. While DWDM Mux/Demux uses wavelengths from 1470nm to 1625nm usually with channel space of 0.8nm (100GHz) or 0.4nm (50GHz). Services or circuits can be added in any order to the Mux/Demux unit.

40ch dwdm mux demux

Monitor Port

Monitor port on CWDM and DWDM Mux/Demux offers a way to test the dB level of the signal without service interruption, which enable users the ability to monitor and troubleshoot networks. If the Mux/Demux is a sing-fiber unit, the monitor port also should be a simplex one, and vice verse.

Expansion Port

Expansion port on WDM Mux/Demux is used to add or expand more wavelengths or channels to the network. By using this port, network managers can increase the network capacity easily by connecting the expansion port with the line port of another Mux/Demux supporting different wavelengths. However, not every WDM Mux/Demux has an expansion port.

dwdm mux demux

1310nm and 1550nm Port

1310nm and 1550nm are one of WDM wavelengths. Many optical transceivers, especially the CWDM and DWDM SFP/SFP+ transceiver, support long runs transmission over these two wavelengths. By connecting with the same wavelength optical transceivers, these two ports can be used to add 1310nm or 1550nm wavelengths into existing WDM networks.

Application Cases of Different Ports on WDM MUX/DEMUX

Although there are several different ports on WDM Mux/Demux, not all of them are used at the same time. Here are some examples of these functioning ports in different connections.

Example One: Using 8 Channels CWDM Mux/Demux with Monitor Port

cwdm mux demux with monitor port

This example is a typical point-to-point network where two switches/routers are connected over CWDM wavelength 1511nm. The CWDM Mux/Demux used has a monitor port and 1310nm port, but the 1310nm does not put into use. In addition, an optical power meter is used to monitor the power on fibers connecting the site A and B.

Example Two: Achieve 500Gbps at Existing Fiber Network with 1310nm Port

dwdm mux with 1310nm port

In this example, two 40 channels DWDM Mux/Demux with monitor port and 1310nm port are used to achieve total 500Gbps services. How to achieve this? First, plug a 1310nm 40G or 100G fiber optical transceiver into the terminal equipment, then use the patch cable to connect it to the existing DWDM network via the 1310nm port on the DWDM Mux/Demux. Since the 1310nm port is combined into a 40 channels DWDM Mux, then this set-up allows the transport of up to 40x10Gbps plus 100Gbpx over one fiber pair, which is total 500Gbps. If use 1550nm port, then the transceiver should be available on the wavelength of 1550nm.

Example Three: Stack Two CWDM MUX/DEMUX Using Expansion Port

cwdm mux with expansion port

The connection in this example is similar to the last one. The difference is that this connection is achieved with expansion port not 1310nm port. On the left side in the cases, a 8 channels CWDM Mux/Demux and a 4 channels CWDM Mux/Demux are stacked via the expansion port on the latter Mux/Demux. And the two 4 channels CWDM Mux/Demux are combined with the line port. If there is a need, more Mux/Demux modules can be added to increase the wavelengths and expand network capacity.

Summary

Different ports on the CWDM and DWDM Mux/Demux have different functions. Knowing more their function is helpful in WDM network deployment. FS.COM supplies various types of CWDM and DWDM Mux/Demux for your preference. And customer services are also available. If you have any needs, welcome to visit our website www.fs.com.

How to Realize Single Fiber Connection in WDM System?

As we all know, fiber optical networking has two transmission ways: dual fiber transmission and single fiber transmission. The difference between them is that the former one requires two fibers—one is for transmitting and the other is for receiving, while the latter only uses one fiber for both transmitting and receiving. Single fiber transmission emergence reduces network deployment cost, especially in WDM systems. This blog intends to introduce how to achieve single fiber connections in CWDM and DWDM networks.

Understanding Single Fiber Transmission

Single fiber transmission, also called bidirectional (BiDi) transmission, sends data in both directions with one strand fiber. For enterprise networks or telecom networks providers who are with limited budgets and fiber capacity, the single fiber transmission is no doubt an ideal choice.

In addition, single fiber transmission is popular in many places.

  • Point to Point, Ring or linear Add and Drop, where installing new fiber is difficult or expensive
  • Enable segmentation of the enterprise traffic over 2 different fibers rather than using the same fiber for both segments
  • Increase reliability to an existing dual fiber solution by using one fiber for working and one for protecting
Single Fiber Solution in CWDM Systems

CWDM technology enables multiple channels (wavelengths) to be transmitted over the same fiber cabling and is able to provide a capacity boost in metro and access networks. Each channel carries data independently from each other, which allows network providers to transport different data rates and protocols (T1, T3, Ethernet, Serial, etc) for different customers or applications. Then how to achieve single fiber transmission in CWDM networks?

Here is an example of single fiber solution in CWDM system.

8-ch-single-fiber-cwdm-mux-demux

The above picture shows how different CWDM wavelengths are transmitted in a single fiber CWDM link. In this link, two 8CH CWDM Mux/Demuxs are required to transmit sixteen different wavelengths. At site A, there is a single fiber 8CH CWDM Mux/Demux using eight wavelengths for transmitting and the other different eight wavelengths for receiving. At site B, another 8CH single fiber CWDM Mux/Demux is deployed. But the wavelengths for TX and RX are reversed. And one single fiber connects the two CWDM Mux/Demux.

Notes: the use of transceivers connected with the CWDM Mux/Demux should be based on the wavelength of the TX side.

Single Fiber Solution in DWDM Systems

DWDM is an optical multiplexing technology to increase bandwidth over existing fiber optic networks, especially in long haul transmissions. And it can support more channels and higher traffic services such as 40G, 100G of LAN/WAN. Since the cost of DWDM components is high, the single fiber transmission is necessary.

DWDM single fiber transmission can be achieved with the use of single fiber DWDM Mux/Demux. As the following picture shows.

DWDM single fiber solution

The picture shows a single fiber 8CH DWDM Mux/Demux with expansion port used for single fiber transmission. Similar to the single fiber CWDM Mux/Demux above, this DWDM Mux/Demux also uses eight wavelengths for transmitting and another eight wavelengths for receiving. In general, the DWDM Mux/Demux should be used in pairs in single fiber bi-directional transmission, and the Mux/Demux port for specific channel must be reversed. Besides, more channels can be added into the links with the expansion port.

This 8CH DWDM Mux/Demux single fiber solution allows extremely high utilizing of a single fiber strand to pass up to 16 wavelengths, optimizing the use of fiber optic cables. And in long distance transmission, optical amplifier also can be utilized.

FS.COM Single Fiber Solution

FS.COM supplies various single fiber CWDM & DWDM Mux/Demux and optical transceivers. Here is part of our Mux/Demux products.

Single Fiber CWDM & DWDM Mux/Demux Product ID Operating Channel
cwdm mux-demux 43779 Tx/Rx:1310/1290, 1350/1330, 1390/1370, 1430/1410, 1490/1470, 1530/1510, 1570/1550, 1610/1590
DWDM mux-demux 50117 Tx/Rx:C21/C22,C23/C24,C25/C26,C27/C28, C29/C30,C31/C32,C33/C34,C35/C36